SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfb2249dfad4f0db8c4085b806d8813b9a524ebda294bb9ae894e192a737afad' 
  AND token = 'LwotMfsIWJJZJFNVn0fbTt+j7WqdxxMrpN5cdfUyqKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}